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Availability of a wide variety of Web services over the Internet offers opportunities of providing new value added services by composing existing ones. Service composition poses a number of challenges. A composite service can be very complex in structure, containing many temporal and data-flow dependencies between the component services. It is highly desirable therefore to be able to validate that a given composite service is well formed: proving that it will not deadlock or livelock and that it respects the sequencing constraints of the constituent services. In this paper, we propose an approach of composition analysis and verification based on Colored Petri nets (CP-nets), which is an extended version of Petri Nets, which have a sound mathematical semantics and a number of existing analysis tools. We provide translation rules of web composition language into CP-nets and a technique to analyze and verify effectively the net to investigate several behavioral properties. Our translation technique is essentially independent of which language we describe composition. As an example, to show the effectiveness of our technique, we pick up BPEL and translate the BPEL specification into CP-nets in a constructive way. These nets are analyzed and verified as prototypes of the specification. [ABSTRACT FROM AUTHOR]

A number of web services are now available and it therefore seems natural to reuse existing web services to create composite web services. The pivotal problems of web services composition are how to model the input and output data dependency of candidate web services and how to satisfy that of a service request by composition efficiently. In this paper we present the concept of "invocation layer" based on data dependency between web services invocation and design the algorithms to get the least invocation layers of candidate web services satisfying the given service request. [ABSTRACT FROM AUTHOR]

The numerous Web services in existence and complex service requests make it natural to compose simple Web services to get value-added composite ones. In this paper, we present an approach driven by Model Driven Architecture (MDA) to develop composite Web services: using UML Class diagram to model structure PIMs (Platform Independent Models) and UML Activity diagram to model behavior PIMs; then converting the PIMs to specific Web services specification platforms and execution platform to get the corresponding PSMs (Platform Specific Models) by model transformation. [ABSTRACT FROM AUTHOR]

Current Web services composition proposals, such as BPEL, BPSS, BPMN and WSCI, provide notations for describing the control and message flows in Web service collaborations. However, such proposals remain at the descriptive level, without providing any kind of mechanisms or tool support for verifying the composition specified in the proposed notations. In this paper, we present to analyze and verify Web services composition by using CP-nets. CP-nets combine the strengths of Petri nets with the expressive power of high-level programming and have sound mathematical semantics. These services composition proposals can be transformed by model transformation rules into CP-nets, which can be used to analyze the performance and to investigate behavioral properties by CP-nets specialized tools. [ABSTRACT FROM AUTHOR]

Current Web services composition proposals, such as BPEL, BPSS or WSCI, provide notations for describing the control and message flows in service collaborations. However, they remain at the descriptive level, without providing any kind of mechanisms or tool support for verifying the composition specified in them. In this paper, we present an approach based on CP-net formalism to analyze and verify Web services composition. We provide translation scheme from composition language into CP-nets and the techniques to analyze and verify effectively the CP-nets to investigate several behavioral properties. Our approach is essentially independent of the language describing composition. As an example, to show the effectiveness of our technique, in this paper, we present the transformation of WSCI to CP-nets, which can be analyzed, verified and simulated as prototypes of WSCI models by the CP-net tools. [ABSTRACT FROM AUTHOR]